1. Field of the Invention
The present invention relates to an RFID (Radio Frequency Identification) system.
2. Description of the Related Art
When electric cables are laid in plants, railways and buildings, work specifications are prepared from design circuit diagrams. While referring to the work specifications, workers perform laying, connecting, testing and removing operations. The operations are progressed as follows. First, the workers lay cables in a plant, for example, while referring to work instructions indicating the start point and the end point of each cable. FIG. 2 illustrates sequence information printed on paper and shows a sequence for a part of the entire plant. FIG. 3 illustrates information complementing the sequence information in FIG. 2 and shows a connection diagram of terminal blocks and cable wires which is printed on paper. The connecting and disconnecting operations are carried out while referring to FIG. 3. After the connecting and disconnecting operations, a sequence test is performed while referring to FIG. 2.
From the viewpoint of ensuring high reliability, human errors have to be eliminated from such cable laying work. Checking the operation results repeatedly is one solution, but repeated check leads to an increase of cost. In addition, such a solution cannot completely eliminate human errors because of just resorting to high consciousness of the individual workers.
To overcome that problem, Patent Document 1 (JP,A 2003-114247) discloses a technique of writing wiring information in an RFID (also called an RFID tag as required) and attaching it to a cable. Also, Patent Document 2 (JP,A 2004-349184) discloses a technique of attaching an RFID to a cable, incorporating the reader function in the terminal block side, and issuing an alarm if improperly wired connection is found. The former known technique employing the write type RFID is disadvantageous in tending to cause a failure and being troublesome due to the necessity of rewrite each time the situation is changed. Also, the latter known technique has a problem that the incorporation of the reader function in the terminal block increases the cost.